A new steroidal saponin, timosaponin F, along with six known compounds was isolated from the rhizomes of Anemarrhena asphodeloides Bge. On the basis of chemical and spectroscopic evidence, the structure of timosaponin F was elucidated as (5beta, 25 S):-spirostan-3beta,15alpha,23alpha-triol-3-O-beta- glucopyranosyl-(1--->2)-beta-galactopyranoside. The six known compounds were anemarrhenasaponin I, anemarrhenasaponin Ia, timosaponin BI, timosaponin BII, timosaponin B, timosaponin AIII; their effects on superoxide generation are also reported.